Method and printing apparatus to print a continuous printing substrate with controlled liquid film quantity given changing print speed

Abstract

In a method and printing apparatus to print a continuous printing substrate, a liquid film with toner and courier fluid is transported to a charge image carrier to develop charge images into toner images. Transport pairs are used comprising rotating transport members in the transport of the liquid film to the charge image carrier and from the charge image carrier to the printing substrate. Given a changing print speed of the printing apparatus at least one of the respective transport pairs is adjusted to provide a respective separation of the transport members from one another so that a substantially same quantity of the liquid film is always conveyed by the respective transport pair.

1. A method to print a continuous printing substrate with an electrophoretic printing apparatus, comprising the steps of:
 transporting a liquid film with toner and carrier fluid to a charge image carrier to develop charge images on said charge image carrier into toner images, and in which the toner images in the liquid film are transfer-printed onto the printing substrate; 
 using transport pairs comprising rotating transport members in the transport of the liquid film to the charge image carrier and from the charge image carrier to the printing substrate; and 
 given a changing print speed of the printing apparatus, for every transport pair adjusting a respective separation of the transport members from one another so that a substantially same quantity of the liquid film is always conveyed by the respective transport pair, and wherein a desired value for the separation of the transport members of the respective transport pairs from one another is stored in a table depending on the print speed, a real value of the separation of the transport members of the respective transport pairs from one another being measured, the real value being compared with the desired value, and the separation of the transport members of the respective transport pair being modified to the desired value given deviation of the real value from the desired value. 
 
     
     
       2. The method according to  claim 1  in which belts are used as at least some of said transport members to transport the liquid film. 
     
     
       3. A method to print a continuous printing substrate with an electrophoretic printing apparatus, comprising the steps of:
 transporting a liquid film with toner and carrier fluid to a charge image carrier to develop charge images on said charge image carrier into toner images, and in which the toner images in the liquid film are transfer-printed onto the printing substrate; 
 using transport pairs comprising rotating transport members in the transport of the liquid film to the charge image carrier and from the charge image carrier to the printing substrate; 
 given a changing print speed of the printing apparatus, for every transport pair adjusting a respective separation of the transport members from one another so that a substantially same quantity of the liquid film is always conveyed by the respective transport pair; and 
 at least the following transport pairs comprising roller pairs being used to transport the liquid film to the printing substrate 
 an anilox roller and a developer roller to convey the liquid film to the developer roller, 
 the developer roller and a photoconductor drum as a roller to convey the liquid film past the photoconductor drum, and 
 the photoconductor drum and a transfer roller to convey the liquid film containing the toner images to the printing substrate. 
 
     
     
       4. The method according to  claim 3  wherein at least one roller of a respective roller pair is borne such that it can be displaced relative to the other roller of the roller pair, and wherein a displacement unit that adjusts the separation of the rollers of the roller pair depending on the print speed is associated with the one of the rollers of the roller pair. 
     
     
       5. The method according to  claim 4  wherein the displacement unit comprises a pressure cylinder, a piston actuated by the pressure cylinder and coupled with an axle of the one roller, and a control unit adjusting a pressure in the pressure cylinder, wherein the control unit adjusts the pressure in the pressure cylinder depending on the print speed. 
     
     
       6. The method according to  claim 4  wherein said displacement unit comprises a linear actuator arranged between the rollers and to which an electrical voltage is applied, the voltage being varied depending on the print speed. 
     
     
       7. The method according to  claim 6  wherein a piezocrystal is provided as said linear actuator. 
     
     
       8. The method according to  claim 4  wherein said displacement unit comprises a step motor, a step count and a step size of which are varied depending on the print speed, said step motor being coupled with the one roller of the roller pair. 
     
     
       9. The method according to  claim 4  in which two of said displacement units are provided, a first arranged at one side of an axle of one of the rollers to be displaced, and the other displacement unit being arranged at an opposite side of the axle of the other roller to be displaced.